Insurance-Approved Locks UK

Almost every UK home insurance policy has a 'security requirements' or 'minimum standards of security' clause. These clauses define the lock standards your property must meet for the policy to pay out on a theft claim. The most-referenced standard is BS3621 — the British Standard for thief-resistant 5-lever mortice deadlocks. Many insurers additionally require TS007 3-star anti-snap cylinders on UPVC and composite doors.

If your locks don't meet the standard, an insurer can decline to pay out after a break-in, even if you have an active policy. This isn't theoretical — it happens regularly. Reading the policy summary carefully before any incident is the only protection.

BS3621 is the British Standard for thief-resistant locks. In practical terms it means a 5-lever mortice deadlock that has been independently tested against drilling, picking, sawing, and brute-force attack. The Kitemark for BS3621 is a small stylised K-shape stamped into the brass faceplate of the lock — usually visible on the door edge when the door is open. Below or beside the Kitemark you should see the marking 'BS3621' followed by a year (e.g. BS3621:2007 or BS3621:2017).

If you see the Kitemark and the BS3621 marking, the lock is compliant. If the faceplate is bare, or the marking says BS3621 with no Kitemark, the lock is not compliant.

TS007 is the British Kitemark standard for euro cylinders, with a 1, 2 or 3 star rating. 3-star cylinders pass independent attack testing for snapping, picking, drilling, and bumping. Look at the front of the cylinder where the key goes in — there should be a small Kitemark with a star count.

1-star cylinders have limited anti-snap protection and are usually only acceptable when paired with 2-star door furniture. 2-star cylinders have built-in anti-snap. 3-star is the highest grade and the modern minimum we recommend on every UPVC and composite door. Many insurers now specifically require 3-star on UPVC.

Aviva, Direct Line, AXA, LV, More Than, and most comparison-site brands all reference BS3621 in their standard household wording for wooden and composite doors with mortice locks. For UPVC and composite doors with multipoint locking, they additionally require TS007 3-star anti-snap cylinders. The exact wording varies — read your policy summary under 'security requirements' or 'minimum standards of security'.

Some insurers offer a premium discount of 5-10 percent for documented BS3621 + TS007 3-star upgrades. After a burglary claim, insurers commonly request a written security upgrade certificate from a qualified locksmith before settling. Some insurers explicitly refuse to settle a break-in claim where the cylinder snapped and was below 3-star.

Open your front door. Look at the edge of the door, at the metal faceplate where the deadbolt slides out. Find the Kitemark and the BS3621 marking. Repeat for every external door. Note any door that's missing the Kitemark.

For UPVC and composite doors, look at the front of the cylinder where the key goes in. Find the small Kitemark with a star count. Confirm 3-star on each cylinder. Note any cylinder that's 2-star, 1-star, or unmarked.

Check accessible windows for functional key locks. If keys are missing or locks are broken, note them.

Then read your policy summary — search for 'BS3621', 'thief-resistant', or 'security requirements'. Match what you have against what's required.

Fitting a new BS3621 mortice lock to an existing wooden door costs £150-180 fitted, including parts. The job takes 1-2 hours per door because the existing mortice may need to be enlarged or re-cut to fit the new lock body.

TS007 3-star anti-snap cylinder fitting on a UPVC door takes 30 minutes per cylinder and costs £120-180 fitted depending on brand (Brisant Ultion, Avocet ABS, Mul-T-Lock are the well-regarded options).

A typical 3-bedroom UK home with two external doors costs £270-540 for a full insurance-grade upgrade. We provide a written security upgrade certificate at no extra cost — keep it with your insurance documents.

The Yale rim latch on the front door is not enough on its own. Most insurers require both a Yale rim AND a BS3621 mortice on a wooden front door. The mortice carries the security load.

Many cheap mortice locks look the part but lack the Kitemark — they're not BS3621 even if they look similar. Check carefully.

Front door is upgraded but back door isn't. Insurers care equally about every external door. The back door is often the weak point.

TS007 cylinder is fitted but only 1-star or 2-star. Some insurers now specifically require 3-star on UPVC. Verify the star count, not just the presence of a Kitemark.

Window key locks are missing or broken on accessible windows. Many policies require functional locks on accessible (ground floor and first floor with flat-roof access) windows.

After a break-in claim, most UK insurers require a written security upgrade certificate from a qualified locksmith before settling. The certificate lists each lock fitted, the standard it meets, the date of fitting, and the engineer's qualifications. We provide this certificate as standard at no extra cost — keep it with your insurance file. It's also useful at next renewal as evidence of compliance.